Effects of Culture Conditions on Mycelial Growth and Luminescence inPanellus Stypticus

Bioluminescence characteristics of a tropical terrestrial fungus (Basidiomycetes)

Freshly collected samples of luminous mycelium of a terrestrial fungus from Panama were investigated for their bioluminescence characteristics. Taxonomic identification of fungal species could not be determined because of the lack of fruiting bodies. Fluorescence excited by 380 nm illumination had an emission spectrum with a main peak at 480 nm and additional chlorophyll peaks related to the wood substrate. Bioluminescence appeared as a continuous glow that did not show any diel variation. The light production was sensitive to temperature and decreased with temperatures higher or lower than ambient. Bioluminescence intensity was sensitive to hydration, increasing by a factor of 400 immediately after exposure to water and increasing by a factor of 1 million after several hours. This increase may have occurred through dilution of superoxide dismutase, which is a suppressive factor of bioluminescence in fungus tissue. The mycelium typically transports nutritive substances back to the fruiting body. The function of luminescent mycelium may be to increase the intensity of light from the fungus and more effectively attract nocturnal insects and other animals that serve as disseminating vectors for fungal spores.

The effect of culture conditions on the mycelial growth and luminescence of naturally bioluminescent fungi

The effects of temperature, light and pH on mycelial growth and luminescence of four naturally bioluminescent fungi were investigated. Cultures of Armillaria mellea, Mycena citricolor, Omphalotus olearius and Panellus stipticus were grown at 5 degrees C, 15 degrees C, 22 degrees C and 30 degrees C, under 24 h light, 12 h light/12 h dark and 24 h dark, and at a pH ranging from 3.5 to 7 in three separate experiments. Temperature and pH had a significant effect on mycelial growth and bioluminescence, however light did not. Bioluminescence and mycelial growth were optimum at 22 degrees C and pH 3-3.5, the exception being M. citricolor for which bioluminescence and growth were optimum at pH 5-6 and pH 4, respectively. With the exception of M. citricolor, bioluminescence and mycelial growth were greater under 24 h darkness. An understanding of the effect of culture conditions on mycelial growth and luminescence is necessary for the future application of bioluminescent fungi as biosensors.

Structure and non-enzymatic light emission of two luciferin precursors isolated from the luminous mushroom Panellus stipticus

The chemical structure of two luciferin precursors PS-A and PS-B, isolated from the luminous mushroom Panellus stipticus, were determined as 1-O-decanoylpanal (2) and 1-O-dodecanoylpanal (3), respectively. Both PS-A and PS-B were converted into chemiluminescent luciferins by treatment with 50 mmol/l methylamine in a pH 3.5 buffer solution containing an anionic surfactant Tergitol 4 at 25-35 degrees C. The luciferins emitted chemiluminescence in a pH 7-8 buffer solution containing a cationic surfactant in the presence of O2 and O2-.

In vitro antagonism of bioluminescent fungi by Trichoderma harzianum

Two species of bioluminescent fungi, Panellus stypticus and Omphalotus olearius were placed in contact with three different strains of interfungal pathogenic Trichoderma harzianum. Subsequent light emission by the luminous fungi and advance of the interfungal pathogens were compared. Relative differences among the pathogens were reflected in their rate of mycelial advance, the total area over which they produced spores upon the host fungi, and decreases in host bioluminescence. After ten days differences in the total surface areas of spore production varied from 1 to 53 per cent. Differences in the reduction of bioluminescence of the same material ranged over 2 orders of magnitude. Final reduction in luminescence ranged over 6 orders of magnitude. A marked reduction in bioluminescence was observed to precede the advance of spore production. The greatest reduction in luminescence was correlated with the presence of T. harzianum hyphae. Two strains of T. harzianum, NRRL 1698 and ATCC 58674, were effective against both bioluminescent fungi within the study period while a third strain, NRRL 13019, was only effective against Omphalotus olearius.